1. Field of the Invention
The present invention relates to the development and production of a storage apparatus for adopting a magnetic recording method such as a magnetic disc apparatus and more specifically it relates to an apparatus and a method of measuring the write magnetic field of a recording head.
2. Description of the Related Art
It is an object to develop a recording head with a narrow core width to form an effective flux transition in a predetermined track width of a magnetic recording medium with the increase of a recording density in a magnetic disc apparatus.
The purpose of a recording head is to output a line of magnetic force generated by the electric current flowing a coil from the write gap between an upper magnetic pole and a lower magnetic pole to a free space, and to form a flux transition on a magnetic recording medium using the magnetic interaction between the line of magnetic force and a magnetic layer on the magnetic recording medium opposing the write gap. Therefore, it is ideal that the line of magnetic force is outputted only from the write gap.
However, since magnetic permeability is not infinite in an actual magnetic pole material, the leakage of a line of magnetic force from the magnetic pole unit other than the write gap is inevitable. Especially, a trailing edge unit (upper magnetic pole) passing on the medium later than the write gap has a size seventh to tenth the size of the write gap. Therefore, there arises a problem such that data of adjacent tracks is erased by a leakage magnetic field (that is, trailing magnetic field) in the case where a recording head is used at a skew angle to the central line of a track.
In order to develop a recording head for a high density recording, the development of a method of measuring the magnetic filed distribution in the vicinity of a recording head simply and non-destructively is required. As for this method, conventionally, a head magnetic field is estimated by the simulation using electromagnetic field analysis software but recently the following method is being established.    (1) Visualization technology of a head magnetic filed using a transmission electron microscope and an image processing (refer to, for example, non-patent literature 1)    (2) Space distribution visualization technology of a head magnetic filed using a horography electron microscope (refer to, for example, patent literature 1)
In addition, a spin-stand with a servo function for positioning a recording head with high precision (for example, a patent literature 2).    [Non-patent literature 1]
“Visualization of recording magnetic field of a magnetic head using a nanometer scale” [online], news release of Hitachi, Ltd. [retrieved on Apr. 12, 2004], via the Internet <URL: http://www.hitachi.co.jp.New/cnews/2002/0624a/0624a.pdf>    [Patent literature 1] Japanese patent application publication No. 2003-248910    [Patent literature 2] Specification of U.S. Pat. No. 6,023,145
In the conventional measurement method using an electron microscope, there is a problem such that expensive equipment is required and destructive inspection is performed in all the methods. In the case of destructive inspection, the electromagnetic conversion characteristic cannot be estimated while a magnetic head used for measurement is mounted on an actual magnetic disc apparatus and the measured magnetic field distribution is hardly corresponded with the electromagnetic conversion characteristic and so on.